The present invention relates to a method for regenerating silver nitrate impregnated ceramic particles for removing mercury from waste exhaust gases.
In the past a number of methods have been developed for separating gaseous mercury from waste gases which usually used impregnated ceramic particles capable of adsorbing the mercury. Such methods can lower the concentration of mercury in the waste gas to a few .mu.g/m.sup.3. However, the disadvantage of these past methods resides in the fact that these particles must usually be stored in special sanitary landfills after having been charged with mercury. In addition to taking up landfill space, which is in short supply in any case, there is also the danger that the mercury can leach out into the ground water.
AT patent 393,632 teaches a method of separating mercury from waste gases during the burning of waste containing heavy metals in which method zeolite particles impregnated with silver salts are used. Limit values of less than 50 .mu.g mercury per cubic meter waste gas can be achieved thereby. The impregnation of the zeolite particles with silver salts takes place in a simple manner by spraying with waste water obtained from the film and photo industry.
The zeolite particles containing the absorbed heavy metals and mercury are subsequently used to manufacture bricks and clinkers. Recovery of the mercury and of the silver from the zeolite is not provided and the processing of the contaminated zeolite to form bricks and clinkers is very problematic for environmental reasons.
It is an object of the present invention to provide a method for regenerating silver nitrate impregnated ceramic particles used for the removal of mercury from waste gases in which method the mercury is recovered and the ceramic particles can be reused for the adsorption of mercury.